1. Field of Invention
This invention relates to a lighting device used primarily as a warning device or road flare. The device is normally stored in the trunk of an emergency vehicle until it is needed to alert oncoming drivers of a hazard in the road. It is commonly used by first responders such as policeman or fireman however it can be used by private citizens as well. In an emergency the user removes the light from his vehicle and places it in the road to signal to approaching vehicles the fact that a hazard exists. It is common practice for several of these devices to be placed in the roadway forming a wedge to guide approaching vehicles around the hazard. Currently both incendiary and electric road flares are in use.
Federal highway laws controlled by the National Highway Traffic Safety Administration (NHTSA) included primarily in section 125 detail the requirements for warning lights in and around long term hazardous areas and job sites. In general these laws require electric lights that flash from “ON” to “OFF” when alerting drivers of a hazard. Lights that flash from “ON” to completely “OFF” are effective in drawing a driver's attention to a hazard. Flashing lights that flash completely “OFF” are especially effective in drawing a driver's attention and that is why the requirement for flashing lights exists. On the other hand electric lights emitting a steady “ON” light are specified when guiding drivers through a work zone. The steady “ON” lights have a perceived fixed intensity. They continuously communicate to a driver their exact location and are therefore effective in guiding a driver through a work zone. When guiding drivers through a hazard zone “ON-OFF” flashing lights are not normally employed as they can create confusion.
The federal law also requires the electric lights to be positioned from two to four feet above the roadway and mounted on barricades or on cones. These lights are bulky and usually too large to store within the limited space available on many emergency vehicles. In addition if struck by an oncoming vehicle they can damage the vehicle or if projected through the air, strike a first responder.
The federal laws to not apply to short term hazards such as a disabled vehicle or at the scene of a small accident. This results from the fact that it would require excessive time and equipment to set up the safety lights required by federal law for a long term hazard zone when marking a short term hazard.
The devices employed to identify short term hazards must be compact, easy to deploy and easy to retrieve. Historically incendiary road flares have filled this need. Electric road flares are currently replacing them in many situations.
Finally it is noteworthy to realize that emitted light is not always equal to perceived light. This is common knowledge to those in the field of lighting. Throughout this specification we have indicated the differences and how it applies to the concepts.
2. Prior Art
Prior art identification of short term hazard zones includes small electric lights, electric road flares or incendiary road flares that are normally placed directly on the road. The electric road flares are usually designed to be run over by oncoming vehicles without sustaining damage or being projected by an impinging vehicle towards a first responder. These small electric road flares are currently replacing prior art incendiary road flares because they avoid the burn hazards and toxic fumes created by incendiary pyrotechnic devices.
Incendiary road flares have a number of deficits. However incendiary road flares are excellent warning devices as they are highly visible warning devices which both alert and guide oncoming drivers. Incendiary road flares are powerful red light sources, constantly illuminating. During portions of their burn cycle they emit a steady light having a substantially fixed intensity. The incendiary road flare by having a fixed intensity and by being disposed directly on a roadway communicates its exact location relative to a hazard thereby improving a driver's ability to avoid an accident. However, during other portions of their burn cycle they can flare increasing their intensity. Their intensity therefore steps changing its value during their operation. The varying intensity alerts drivers to their presence. Incendiary flares are dangerous and hot. Drivers realize that the incendiary road flares are dangerously hot and tend to respect them. Drivers move as directed when incendiary road flares are in position.
The prior art electric flares currently being substituted for incendiary flares are not as effective in controlling traffic as the incendiary flares. Many are far less intense. All have light emission patterns differing from the substantially steady on, continuously emitting and randomly varying light of the incendiary flares. The prior art electric flares do not, like incendiary flares, both alert and guide oncoming drivers.
Prior art designs employ either a single led light source or a plurality of led light sources in a circle. The single led light source design is usually less expensive to manufacture. The prior art electric flares having a single led light source are either steady “ON”, flashing from full “ON” to full “OFF” or flickering rapidly from “ON” to “OFF”. When in the flashing mode and in the “ON” zone of its waveform the flashing light can have a dwell time long enough for a driver to progress towards perceiving the light as having a fixed intensity. Unfortunately, when in the “OFF” zone of its waveform the dwell time is usually also long such that the light visually disappears. The long “OFF” zone of the flashing waveform which follows the “ON” time ceases communication with the driver for an unacceptably long time such that the drivers eyes wander thereby losing his progress in establishing and exact location for the light or the hazard. In addition a group of flashing lights combine to make it more difficult for a driver to focus on any one of the lights to discern its fixed intensity.
If the period of the flash cycle of a light in a flash mode is reduced the light will be perceived first as a rapidly pulsing light then as a flickering light neither of which would be perceived as having a fixed intensity. A rapidly pulsing light is perceived as emitting a light having an effect between flashing and flickering whereby it visibly changes from “ON” to “OFF” but changes quickly such that its “ON” zone is not perceived as having a fixed intensity.
In the perceived steady “ON” mode of the prior art single led the led is usually not continuously emitting light but is pulsed from full “ON” to full “OFF” with an “ON” dwell time or “ON” zone of approximately 2 milliseconds and an “OFF” dwell time or “OFF” zone of approximately 3 milliseconds. The human eye integrates this pulsing light and, due to its short 5 millisecond period, perceives a steady “ON” warning light having a fixed intensity. This high frequency pulse light which is perceived as a steady light having a perceived fixed intensity is excellent for guidance as is an emitted steady “ON” light, however like an emitted steady light is inadequate for alerting.
In the flickering mode of the single led prior art design, the emitted light is controlled by a microcontroller such that the led lamp is flashing from full “ON” to full “OFF” with random pulses such that its “ON time varies from approximately 5 to 30 milliseconds and its “OFF” time varies from approximately 5 to 30 milliseconds. In this prior art design the “ON” and “OFF” times of the led are such that the human eye integrates the pulses to visualize a light that is continuously emitting but is not perceived as a steady light because it has no perceived fixed intensity. It is, in fact, visualized as a constantly changing intensity. This flicker mode, like a slow pulsing or flashing mode, is good for alerting but due to its constantly changing perceived intensity, can confuse a driver attempting to establish its exact position for guidance past a hazard. This prior art design could have the frequency of the pulses of the flicker mode decreased such that the “ON” time for the led was sufficient for a driver to perceive a fixed intensity and establish the exact location of the light. However decreasing the frequency would also lengthen the “OFF” time making the design a typical flashing light with the emitted light perceived as either steady “ON” or fully “OFF”.
This perception of a rapidly pulsing light as a steady light is to be expected and is described in numerous technical sources including the reference book of the Illuminating Engineering Society. Specifically, when a rapidly pulsing light is pulsed at a frequency which exceeds a parameter identified as the critical flicker frequency relative to that design the human eye perceives the pulsing light as steady light. The exact value of the critical flicker frequency for a design depends upon a number of factors including intensity and waveform. The frequency of the pulses in the steady “ON” mode of the prior art design far exceeds the critical flicker frequency of that waveform and therefore the prior art pulsing light is perceived as a steady light having a perceived fixed intensity.
Similarly, in the flicker mode of the prior art design the led is not “ON” constantly but pulsing rapidly from “ON” to fully “OFF”. The stated objective of this prior art design is a flicker mode. This flicker effect is achieved by designing the pulse frequency to be less than the critical flicker frequency. Using this design frequency the emitted light is perceived by the human eye as flickering. A flickering light is good for alerting. However as long as it is flickering it is not perceived by the human eye as having a fixed intensity. A perceived flickering light having no zone or portion of its cycle discernable as a fixed or discrete intensity fails to convey its exact location to an oncoming driver. It fails to provide a portion of its cycle having the steady light or visually fixed intensity necessary to accurately establish its location. A plurality of flickering lights further adds to the confusion as a driver looks for guidance past a hazard.
The single led prior art design offers three separate waveforms of emitted light defined as operating modes including, a pulsed steady “ON”, a pulsed “FLASH” and a pulsed “FLICKER” mode. It does not disclose a single mode or waveform combining the prior art modes to improve the effectiveness of the light by both alerting and guiding oncoming drivers.
A second type of prior art electric flare employs a plurality of led light sources positioned in a circle. The plurality of led light sources are energized in sequence to create a rotating effect. In this rotating effect design each led lamp actually flashes from “ON” to “OFF” with the sequential illumination creating the rotating effect. Prior art flares having a rotating effect can confuse rather than guide oncoming drivers.
The prior art rotating effect designs usually also include the option of simultaneously flashing the entire circle of led light sources from “ON” to completely “OFF” or simultaneously energizing the entire circle using a high frequency pulse to create a perceived steady “ON” mode. It is noteworthy to realize that the prior art rotating effect electric road flares and the single led light source road flares both usually incorporate an led light source, a power controller, a power supply and a housing. In addition the power controller is usually a microcontroller which is a programmable computer. It would therefore be possible for prior art to adjust their computer program to include a perceived steady light having a discrete intensity combined with a stepped intensity to achieve the objectives of the present invention. They have not included this option as part of their design.
The prior art electric road flares have steady or flashing modes similar to the lights meeting federal laws regarding long term hazards. They perform as either guiding or alerting warning devices but not both simultaneously as is accomplished by both the incendiary road flare and the present invention.
The prior art road flare light emission patterns are not visually similar to the incendiary flares and therefore they do not receive the drivers respect required for this type of warning device.
Prior art does not include the additional features:                Prior art does not provide an electric road flare having a housing for disposition on a roadway, emitting a light perceived as a steady light during a first multiplicity of zones of its waveform and emitting a visible light perceived as different from said perceived steady light during a second multiplicity of zones of its waveform. The second multiplicity of zones alternating with the first multiplicity of zones thereby providing an alerting signal as well as guidance about a fixed hazard.        Prior art does not provide an electric road flare having a housing for disposition on a roadway, emitting a light perceived as a steady light during a first multiplicity of zones of its waveform and emitting a visible light perceived as a flickering light during a second multiplicity of zones of its waveform. The second multiplicity of zones mixed with the first multiplicity of zones thereby providing an alerting signal as well as guidance about a fixed hazard.        Prior art does not provide an electric road flare having a housing for disposition on a roadway, emitting a light perceived as a lower intensity steady light during a first multiplicity of zones of its waveform and emitting a light perceived as an upper intensity steady light during a second multiplicity of zones of its waveform. The second multiplicity of zones mixing with the first multiplicity of zones thereby providing an alerting signal as well as guidance about a fixed hazard.        Prior art does not provide an electric road flare having a housing for disposition on a roadway, emitting a light perceived as a steady light during a first multiplicity of zones of its waveform and emitting a visible light perceived as a pulsing light during a second multiplicity of zones of its waveform. The second multiplicity of zones alternating with the first multiplicity of zones thereby providing an alerting signal and guidance about a fixed hazard.        Prior art does not provide an electric road flare having a housing for disposition on a roadway, emitting a light perceived as a steady light during a first multiplicity of zones of its waveform and emitting a visible light perceived as a flashing light during a second multiplicity of zones of its waveform. The second multiplicity of zones mixed with the first multiplicity of zones thereby providing an alerting signal and guidance about a fixed hazard.        Prior art does not provide a group of electric road flares for disposition on a roadway, each flare emitting a continuously visible light having a multiplicity of alerting signal zones mixed or alternating with a multiplicity of perceived steady light or fixed intensity zones thereby providing a plurality of alerting signals and a distinct visual line of lights for guidance about a fixed hazardous zone        